Surgical techniques for the reconstruction of the anterior cruciate ligament (ACL) within the knee joint have typically involved creating osseous tunnels open at each end in the tibia and femur. One end of a synthetic or natural graft is placed into and anchored in each respective tunnel with the graft in tension. The graft extending between the femur and tibia thus serves as a replacement for the ACL. Such a procedure has commonly involved surgical incisions both above and below the knee to provide access to the femoral and tibial tunnel openings. In such surgery a tool which has been commonly used is a device sold by W. L Gore & Associates and known by the trademark "GORE SMOOTHER CRUCIAL TOOL." This tool is a multi-function disposable instrument that serves:
1) as a trial prosthesis for assessment of the intercondylar notch,
2) to smooth the intercondylar notch and drill hole edges after drilling,
3) as a measurement gauge for proper selection of graft length, and
4) to engage and place a biologic or synthetic graft.
This prior art tool as shown in FIGS. 7 and 8 is comprised of a flexible main body 51 of silicone elastomer extruded onto stainless steel cable. The exterior surface of the silicone is then printed with measuring marks at 2 centimeter increments. A flexible braid 55 of stainless steel cable in an open pattern covers a major portion of the silicone. A relatively stiff stainless steel segment having an "eye" at its end and encased in polytetrafluoroethylene (PTFE) extends from one end of the main body and forms the leading end 52 of the tool. A flexible aramid fiber loop 53 extends from the other end of the main body as a trailing end of the tool. In use, the surgeon drills entry holes into the patient's tibia, below the joint, and femur, above the joint. The leading end of the tool is introduced into the tibial tunnel, across the knee joint space and into the femoral tunnel to exit laterally on the femur. At this point the trailing end of the tool will still protrude from the tibial tunnel. The main body of the tool is held in tension and slid back and forth through the bone tunnels so that the slightly abrasive surface of the open braid covering the main body may smooth the bone surfaces and edges along the path for the graft. The measuring marks assist in determining proper graft length. Once in place in the graft path the device functions as a trial prosthesis by allowing arthroscopic inspection for visual determination of whether the graft position will allow for free joint movement without impingement or interference between any tissue or bone. The flexible loop on the trailing end of the tool is attached to the ACL graft which is then pulled into position within the bone tunnels as the tool is removed through the femoral opening.
More recently, alternative endoscopic surgical techniques for the reconstruction of the anterior cruciate ligament (ACL) within the knee joint have been developed so that the placement of a graft between the femur and tibia may be accomplished using a technique requiring only a single external skin incision. The graft is commonly one continuous piece of tissue taken from the patient's own knee and comprising sections or plugs of patella bone and tibial bone connected by a section of patellar tendon. Accordingly such a graft may be referred to as a "Bone-Patellar Tendon Bone" graft or simply as a "BPTB" graft. In this more recent technique an open tibial tunnel is created to extend upwardly to exit the head of the tibia. This tibial tunnel is oriented so that a blind femoral tunnel may be bored using the tibial tunnel for access when the knee is flexed at, for example, approximately 60 to 80 degrees. Accordingly with the joint flexed, the femoral tunnel is in alignment with the tibial tunnel and creates an essentially straight path for placement of the graft. The obvious advantage to the patient of this improved technique is that it is less invasive since it can completely eliminate the need for an incision in the thigh and the additional trauma and morbidity which may be associated with that incision. However because the path of the graft does not involve two open ended osseous tunnels, the described flexible prior art tool of FIGS. 7-8 is not suitable for use with the improved technique.
The surgical procedure for ACL reconstruction for which the present invention is intended has been described by authors Douglas W. Jackson, MD; Robert Kenna; Timothy M. Simon, MS; and Peter Kurzweil, MD; in "Orthopedics" Volume 16, Number 9, (September 1993) under the title "Endoscopic ACL Reconstruction." The relevant portion of the described procedure is briefly summarized as follows:
Work within the joint itself is viewed arthroscopically and accomplished through anterolateral and anteromedial portals. The respective tunnels are bored in the tibia and femur, with the tibial tunnel exiting the tibial head in the area of the intercondylar eminence. A 2.4 mm eyeloop drill is drilled into place to be used as a guide for a cannulated reamer which creates the femoral osseous tunnel. The eyeloop drill may be drilled completely through the femur and out the anterolateral aspect of the thigh and be used later to pass sutures attached to the graft to pull and guide the graft into place. The blind femoral tunnel is bored beyond, and in alignment with, the tibial tunnel to a depth of approximately 25 mm, or slightly more than the length of the patellar bone plug, by a tool extending through the tibial tunnel with the knee flexed at approximately 70 degrees from the fully extended or "straight leg" orientation. The diameter of the femoral tunnel may initially be somewhat undersized in order to allow adjustment of the tunnel position after the initial drilling.